The moderate wing of the Republican Party was already on its last feathers, but some fearful of a Tea Party takeover hoped blue state Gov. Chris Christie (N.J.) would let them fly again. However, with Christie's political career suddenly in jeopardy, Republican moderates may find themselves with no strong alternatives. And they may start to ask themselves: Why am I still in this party?

As fun as Christie's style may be, any political veteran knows it could easily backfire in the pressure cooker of a presidential campaign.

But if Republican moderates blinded themselves to Christie's weaknesses before out of desperation, they can't miss them today.

Whether or not he is found to be criminally or otherwise directly involved with the Bridgegate controversy that has enveloped his governorship, Christie's national prospects are damaged. The "political thug" narrative is seeping into the public consciousness, and there is plenty of video footage on Christie's own YouTube channel to bolster the case. There is also plenty of reporting left to do on the broader Team Christie effort — previously documented but not widely known — to crassly use taxpayer dollars for the purposes of buying Democratic support or punishing Democratic opponents.

Any donor, strategist, or volunteer deciding whether or not to join Christie '16 is going to pause and wonder if the same ethically dubious, bullying atmosphere will drive — and ultimately sink — a presidential effort.

Rep. Paul Ryan (Wisc.) is also up there, but he reportedly sees his future in the House, not the White House. Former Gov. Jeb Bush (Fla.) would attract moderate support, but he is saddled with an unpopular last name and also is not doing much to suggest he's running. Other previously hyped candidates like Sen. Marco Rubio (Fla.), Gov. Bobby Jindal (La.) and Gov. Scott Walker (Wisc.) — less wacky than Paul or Cruz, but otherwise lacking in moderate trappings — have all made missteps and now poll in single digits.

Which leaves Christie as the firewall protecting the GOP from Cruz or Paul becoming the party's standard-bearer, letting the lunatics run the asylum, and risking a 1964-style blowout loss.

That firewall is already beginning to crack. Any Republican moderate has to ask: If not Christie, then who is left that I can stomach?

If the choice offered by the Republican Party is between an unhinged bully or an unhinged ideologue, it's not much of a choice for a grounded moderate. And if that disgusts you, maybe you're just in the wrong party.